The incorporation of major amounts of builders in liquid detergent compositions poses a significant formulating challenge since the presence of major amounts of builder inevitably causes the detergent composition to phase separate. Builders such as sodium citrate, citric acid, sodium carbonate, and/or alkali metal silicates can only be incorporated in minor amounts in liquid detergent compositions, such amounts being typically below the concentration levels that would cause separation of the surfactant phase. U.S. Pat. No. 5,536,440 and U.S. Pat. No. 5,534,183 (both assigned to BASF) disclose the use of novel hydrophilic copolymers for stabilizing such concentrated built liquid detergent compositions.
Further, liquid detergent formulators are also concerned with metal ions as they diminish the effectiveness of many detergent formulations. Chelating agents are typically employed to complex the metal ions and thereby significantly improve the performance and efficiency of such formulations. Examples of such chelating agents are the polyphosphates such as potassium diphosphate, sodium tripolyphosphate, aminocarboxylates such as nitrilotriacetate, ethylene diamine tetraacetate, diethylene triamine pentacetate, hydroxycarboxylates such as citric acid, gluconic acid, phosphonates such as amino trimethylene phosphonate and ethylene diamine tetramethylene phosphonate. While the chelating agents listed above have moderate to good complexing power, a number of them have limited utility in commercial cleaning compositions. The major limitations are that chelating agents can cause eutrophication even though they have very good metal complexation properties, while others have poor biodegradability. Another drawback with chelating agents is that incorporation of chelating agents in significant amounts in liquid laundry formulations poses a serious formulating challenge. Chelating agents by virtue of their strong ionic character would typically salt out the surfactant in liquid laundry formulations or cause stability problems in formulating liquid laundry compositions. See, DE 4319935 which discloses the preparation and use of carboxylmethylglycine derivatives as comaplexing agents and WO 96/11253 which discloses a sequestering agent comprising amino acids useful in granular peroxy bleach formulations, and JP 0061637 which discloses carboxymethylamino acids as builders in detergent formulations. Currently, the art is faced with the problem of how to incorporate chelating agents into built liquid detergents.
Applicants have surprisingly discovered that biodegradable chelants can be successfully incorporated into built liquid detergent formulations containing Applicants' hydrophilic copolymer. The resultant built liquid detergent formulation is stable.